1. Field of the Invention
The present invention relates to a tear line of a vehicle airbag door, and more particularly to a method of forming a tear line of a vehicle airbag door using an in-mold blade.
2. Description of Related Art
In general, an airbag is installed in front of a driver seat or a passenger seat in order to protect a driver or a passenger when an accident occurs. For example, an airbag provided in front of the passenger seat is typically installed at an upper end of a glove box provided at a lower end of an instrument panel.
According to an airbag device mounted in front of the passenger seat, if an airbag starts deployment, pressure is applied to a door plate, and a tear line around a door cover is torn to deploy the airbag. Here, the door plate is made of a steel material in the range of 0.8 t to 1.2 t, and the door cover and the tear line are made of a plastic material such as crash pad.
FIG. 1 is a view illustrating an airbag door in the related art.
As illustrated in FIG. 1, the airbag door 2 in the related art is assembled on the side of a crash pad 8 in which an airbag module 4 and an airbag 6 are accommodatingly installed.
The airbag door 2 is composed of a crash pad outer skin 10, a crash pad inner skin 12, and a porous form 14. In this case, the airbag door 2 has a tear line 16 on the crash pad 8 to facilitate the separation thereof when the airbag is operated.
The tear line 16 forms a door flange portion 18 that is provided by inwardly bending the edge of the airbag door 2 formed by the crash pad outer skin 10, and a crash pad flange portion 20 is formed on the crash pad 8 that corresponds to the door flange portion 18. Also, on the upper side of the crash pad inner skin 12, a groove portion 22 for facilitating the opening of the airbag door 2 is formed.
Also, a support bracket 24 is put just inside the passenger-side tear line 16 of the crash pad inner skin 12, and an inner end portion 26 of the crash pad inner skin 10 is formed therein to guide the separation when the airbag is expanded. In this case, the inner end portion 26 is cut off from the crash pad flange portion 20 of the crash pad outer skin 10, and thus the opening of the airbag door 2 is facilitated.
The airbag door 2 is opened in a manner that if an airbag electronic control unit (not illustrated) recognizes the occurrence of vehicle collision, an inflator is operated, and the airbag 6 is expanded to open the airbag door 2.
On the other hand, in the case of an invisible passenger-side airbag, a tear line of the passenger-side airbag door (PAB door) that is provided on an inner surface of the instrument panel formed by means of plastic injection for expansion of the airbag, for example, may be pre-molded using in-mold forming, milling process, laser process, and the like. The details thereof will now be described with reference to FIGS. 2 and 4A to 4D.
FIG. 2 is a view illustrating a method of forming a tear line of an airbag door using in-mold forming in the related art.
Referring to FIG. 2, according to the method of forming a tear line of an airbag door using in-mold forming in the related art, a tear line 50 of an airbag door 40 is in-mold molded by applying a “V”-shaped notch to a core mold 31 between the core mold 31 and a cavity mold 32.
Accordingly, the method of forming a tear line of an airbag door using in-mold forming in the related art has the problem that the external appearance of the tear line is bent due to differences in speed of solidification and resin flow speed between a notch portion and a notch neighboring portion, and thus the tear line may be exposed.
FIGS. 3A to 3C are views illustrating a method of forming a tear line of an airbag door using a milling process in the related art.
According to the method of forming a tear line of an airbag door using a milling process in the related art, as illustrated in FIG. 3A, a notch is formed on the tear line 50 on the rear surface of the airbag door 40 by a milling process using a milling head 60 after the airbag door 40 is formed. FIG. 3B illustrates the forming of the tear line 50 on the airbag door 40, and FIG. 3C illustrates a cross-section cut along line A-A of FIG. 3B.
In the method of forming the tear line of the airbag door using the milling process in the related art, the rupture strength of the tear line 50 may be determined by the residual thickness and the intermediate bridge width. In this case, it is required to invest in the processing equipment and a fix jig for post-processing, cost increase due to the process addition may occur, and the quality of the processed surface is not uniform.
FIGS. 4A to 4D are views illustrating a method of forming a tear line of an airbag door using a laser process in the related art.
According to the method of forming a tear line of an airbag door using a laser process in the related art, as illustrated in FIG. 4A, a notch is formed on the tear line 50 on the rear surface of the airbag door 40 by a laser process using a laser head 70 after the airbag door 40 is formed. FIG. 4B illustrates the forming of the tear line 50 on the airbag door 40, and FIG. 4C illustrates a cross-section cut along line B-B in FIG. 4B.
In the method of forming the tear line of the airbag door using the laser process in the related art, the rupture strength of the tear line 50 may be determined by the residual thickness and pitch of a hole processed by laser irradiation. In this case, as illustrated in FIG. 4D, processing equipment 72 and a fix jig 74 for post-processing of the airbag door 40 are additionally required, and thus cost increase due to the process addition may occur.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.